LONDON (Reuters) - A major study on the safety of a mist inhaler used to treat chronic lung disease has found it does not increase the risk of patients dying early, in contrast to an earlier analysis published two years ago.

The reassuring result with a formulation of Boehringer Ingelheim's Spiriva delivered through its new Respimat device is good news for the German drugmaker and potentially for others developing rival products containing so-called LAMA drugs.

Data from the 17,135-patient study, comparing the safety and efficacy of Spiriva Respimat against a formulation of the drug given via the older HandiHaler device, were unveiled at the European Respiratory Society congress in Barcelona on Sunday.

Competitors in the field include GlaxoSmithKline, whose experimental product Anoro combining a LAMA drug with a different kind of treatment called a LABA will be assessed by a U.S. Food and Drug Administration advisory panel on September 10.

The encouraging safety message on Spiriva Respimat may lower the regulatory hurdle for such new LAMA-containing products, industry analysts believe.

Several drugmakers are betting that LABA/LAMA inhalers will become the first choice for chronic obstructive pulmonary disease (COPD), which causes debilitating breathlessness and affects more than 200 million people worldwide.

Other companies working on long-acting beta-2-agonist (LABA) and long-acting muscarinic antagonist (LAMA) combinations include Novartis, which has an alliance with Vectura; AstraZeneca, following its recent acquisition of Pearl Therapeutics; and a partnership of Almirall and Forest Laboratories.

Boehringer itself also has a LABA/LAMA drug in development.

Current market-leading drugs for COPD include Spiriva and GSK's Advair.

Spiriva has been on the market since 2002 but concerns about its safety were aroused in 2011 when a study based on a pooled analysis of previous trials suggested patients taking it via the Respimat device increased their risk of dying by 52 percent compared to those on placebo.

Boehringer and its marketing partner Pfizer disputed the findings at the time.

The new three-year clinical trial found Respimat was just as safe as the older HandiHaler inhaler and that COPD patients enjoyed a median 756 days without a sustained worsening of symptoms against 719 days among those using the HandiHaler. The new trial did not include a placebo group.

Boehringer hopes the new company-sponsored trial - one of the biggest to date in COPD - will draw a line under the safety question and reinforce the benefits of all Spiriva formulations.

The outcome is also important for Boehringer's future ambitions in developing new medicines, including its LABA/LAMA product, since these also rely on the Respimat device.

The new study, which was sponsored by Boehringer, was published simultaneously in the New England Journal of Medicine.